1. Field of the Invention
The present invention relates to an objective lens drive unit for moving an objective lens for converging a light beam to an optical information recording medium such as an optical disk and a magnetooptic disk to record and reproduce information.
2. Description of the Related Art
An optical pickup device generally records and reproduces information from an optical information recording medium such as an optical disk, a magnetooptic disk, etc. The optical pickup device has an objective lens for irradiating a light beam emitted from a light source onto the optical information recording medium as a light spot. The optical pickup device also has an objective lens drive unit for moving the objective lens with respect to the optical information recording medium in focusing and tracking directions.
With respect to the objective lens drive unit, there is a proposed technique for integrally pressing an actuator base and inner and outer yokes. When this proposed technique is used, the actuator base can be precisely manufactured with low cost.
To make an actuator base portion compact, the bending height of an inner yoke portion with respect to the actuator base portion is reduced to shorten a length of the actuator base portion. The inner yoke portion is bent and stretched to increase a height of the inner yoke portion.
When the height of the inner yoke portion is increased by stretch in the above general technique, no upper end of the inner yoke portion is flat and an accuracy in height of the inner yoke portion is reduced. Therefore, an upper yoke is arranged in a slanting state with respect to upper ends of an outer yoke portion and the inner yoke portion so that no upper yoke is suitably fixed to the inner and outer yoke portions.